1. Technical Field
The present invention relates to a printed circuit board and to a method of manufacturing the printed circuit board.
2. Description of the Related Art
Among the various methods for manufacturing a printed circuit board, one method currently being used to manufacture a high-density printed circuit board is illustrated in FIGS. 1A to 1H, which includes forming bumps 3 on a board 2, stacking on an insulation layer 4, and stacking this in turn onto a multi-layer board 1, etc., while applying heat and pressure. This is referred to as a B2it method. With the B2it method, vias for interlayer conduction can be formed in a simple manner, whereby manufacturing efficiency can be increased.
The B2it method includes forming paste bumps, using copper (Cu), silver (Ag), etc., on a copper foil, piling an insulation layer with the copper foil, and then applying heat and pressure for stacking. In the B2it method, the process of printing the paste has to be performed such that the bumps have a height sufficient to penetrate the insulation layer. Thus, as illustrated in FIGS. 2A and 2B, the conductive paste 3a, 3b may be printed on the lands 9 formed on an insulation layer 4′ over a series of four or five repetitions. As such, the repeated printing intended for forming the bumps to a particular height can lower productivity, and can cause spreading at the lower ends of the bumps.